Selective C–O bond cleavage of allylic esters using [MoH4(Ph2PCH2CH2PPh2)2] under light irradiation to give hydridocarboxylatomolybdenum(II) complexes

Abstract

The complex [MoH₄(dppe)₂](1)(dppe = Ph₂PCH₂CH₂PPh₂) reacted with allyl carboxylates RCO₂CH₂CHCH₂(R = H, Me, Et, Prⁿ, Bu^t, CH₂CMe, or Ph) in benzene upon irradiation with a high-pressure mercury lamp to give [MoH(O₂CR)(dppe)₂](2), together with propene and H₂. Reaction pathways comprising the oxidative addition of the allyl carboxylates involving allyl–oxygen bond cleavage are proposed on the basis of the results obtained with substituted allylic esters. The complexes (2) were characterized spectroscopically as having pentagonal-bipyramidal structures in solution. The similar reaction of complex (1) with allyl formate led to selective cleavage of the formic C–H bond to give ultimately the known cis-[Mo(CO)₂(dppe)₂]via(2; R = H).